1. Field of the Invention
The invention relates to a rack guide unit and a steering system including the rack guide unit.
2. Description of the Related Art
Generally, a rack-and-pinion-type steering system is provided with a rack guide unit that reduces a backlash between a rack and a pinion. In the rack guide unit, when a rack guide by which a rack shaft is slidably supported wears out, a compression coil spring interposed between the rack guide and a plug pushes the rack guide toward the rack shaft to compensate for a clearance between the rack guide and the plug.
According to Japanese Patent Application Publication No. 11-43055 (JP 11-43055 A), a coned disc spring is interposed between a rack guide and a plug so as to be installed in series with a compression coil spring. The coned disc spring is deformed to absorb an impact only when an excessively high impact load is input into the coned disc spring.
In FIG. 4 in JP 11-43055 A, the coned disc spring and an intervening member are accommodated and held in a tubular portion formed in the plug. In JP 11-43055 A, the intervening member is referred to as “second rack support”. The intervening member is interposed between the compression coil spring and the coned disc spring. Specifically, the intervening member is held by a snap ring that is fitted in both a circumferential groove formed in the inner periphery of the tubular portion that guides the outer periphery of the coned disc spring and a circumferential groove formed in the outer periphery of the intervening member, and the coned disc spring is held between the intervening member and the bottom of tubular portion.
According to the technique described in JP 11-43055 A, in order to hold the coned disc spring and the intervening member in the plug, a cumbersome work for fitting the snap ring in both the circumferential groove of the plug and the circumferential groove of the intervening member is required. Thus, the total number of man-hours needed to obtain a subassembly of a rack guide unit including the plug is increased. This affects the efficiency of assembly of the rack guide unit.